Automatic Transaxle Diagnosis - 4t80-e Cadillac DeVille Concours

APPLICATION

TRANSAXLE APPLICATION

BODY CODE DESIGNATIONS

DESCRIPTION

The 4T80-E transaxle uses 2 electric solenoids to control transaxle upshifts and downshifts. Transaxles also use a transaxle pressure control solenoid (force motor) solenoid to control line pressure, Transaxle Fluid Temperature (TFT) sensor, pressure switch assembly, 2 speed sensors: Vehicle Speed Sensor (VSS) and Transaxle Input Sensor (TIS), and a lock-up control solenoid for Torque Converter Clutch (TCC) operation. Each solenoid is turned on or off by the Powertrain Control Module (PCM). PCM also includes on-board self-diagnostics. This helps identify which parts or circuits may need further testing.

OPERATION

Each solenoid either holds hydraulic pressure (solenoid on) or releases hydraulic pressure (solenoid off). This action controls shift valves inside valve body. By switching one or both solenoids on or off, different combinations of clutches, sprags and bands are operated. See CLUTCH & BAND APPLICATIONS under TROUBLE SHOOTING.

PCM

On Cadillac models, PCM is located in left corner of engine compartment under air cleaner housing. On Buick and Oldsmobile models, PCM is located under left kick panel. PCM controls ignition, fuel and emission devices related to engine and transaxle upshifts and downshifts.

PCM receives electronic signals from sensors and switches. These signals help PCM determine when to operate various relays and solenoids related to engine and transaxle control.

SENSORS & SWITCHES

PCM controls converter clutch lock-up, upshifts and downshifts based on transmission temperature, system voltage, throttle position, transmission oil pressure switches, and transmission output and input (engine) speed sensors. (Scheme 66) System also includes several other switches and sensors which are used for engine control. These components are covered in appropriate SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE section

1. For 4.6L FWD Cadillac Models, see «SYSTEM/COMPONENT TESTS»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l)
2. For 4.0L Aurora, see «SYSTEM/COMPONENT TESTS»(ref-20351)

Shift Solenoids 1-2 ("A") & 2-3 ("B")

Transmission is shifted up or down by 2 electric shift solenoids. Both solenoids are located on valve body. (Scheme 66) Ignition power is supplied to each solenoid by transmission fuse. Solenoid 1-2 ("A") controls hydraulic pressure to 1-2 and 3-4 shift valves. Solenoid 2-3 ("B") controls hydraulic pressure to 3-2 and 4-3 shift valves.

Pressure Control Solenoid

Pressure control (force motor) solenoid has a spool valve and operates pressure regulator valve. (Scheme 66) PCM sends a frequency signal to pressure control solenoid to regulate hydraulic line pressure. Frequency signal (duty cycle) is measured with a dwell meter or lab scope. When duty cycle is zero, line pressure is at maximum, and pressure control solenoid draws zero amps. When duty cycle is 60 percent, line pressure is at minimum, and pressure control solenoid draws 1.1 amps at 4.5 volts.

TCC PWM Solenoid

This solenoid is used to control TCC apply valve. PCM sends a frequency signal to TCC PWM solenoid to gradually apply or release TCC. (Scheme 66)

Scheme 66

SELF-DIAGNOSTICS

PCM constantly monitors all electrical circuits. If PCM detects circuit problems or sensors out of range, it will record a Diagnostic Trouble Code (DTC). If problem continues for a predetermined time, Malfunction Indicator Light (MIL) will glow.

If MIL is on all the time, DTC(s) are currently being detected. If MIL is off, but PCM had detected a circuit or sensor problem, DTC(s) will be stored in computer memory.

Stored DTCs may be retrieved from PCM memory using a factory recommended Tech 1 scan tool or aftermarket scan tool. DTCs CANNOT be retrieved by grounding 16-pin Data Link Connector (DLC).

Note. Faulty engine sensors and actuators may cause transaxle related DTCs or driveability problems. Engine faults and related DTCs must be diagnosed and repaired before transaxle codes are repaired. For additional information on diagnosing and repairing engine related PCM trouble codes, see appropriate TESTS W/CODES in the ENGINE PERFORMANCE section

1. For 4.6L FWD Cadillac Models, see «TESTS W/CODES»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-control-system-tests-wcodes)
2. For 4.0L Aurora, see «TESTS W/CODES»(ref-20306)

CLUTCH & BAND APPLICATIONS

CLUTCH & BAND APPLICATION CHART (4T80-E)

ELECTRONIC SELF-DIAGNOSTICS

Note. To test electronic control of transaxle solenoids without using self-diagnostics or if self-diagnostics does not function, go to appropriate COMPONENT TESTS under ELECTRONIC TESTING. After repairs are made, DTCs should be erased from computer memory. See CLEARING TROUBLE CODES under ELECTRONIC SELF-DIAGNOSTICS.

Note. Trouble codes will be recorded at various operating times. Some codes require operation of affected sensor or switch for 5 seconds; others may require operation for 5 minutes or longer at normal operating temperature, road speed and load. Therefore, some codes may not set in a service bay operational mode and may require road testing vehicle in order to duplicate condition under which code will set.

RETRIEVING CODES

Note. Stored DTCs may be retrieved from PCM memory using a factory recommended Tech 1 scan tool or aftermarket scan tool. DTCs CANNOT be retrieved by grounding 16-pin Data Link Connector (DLC). Plugging scan tool into DLC, located under instrument panel, enables user to read DTCs and check voltages in system on serial data line.

Scan tools may also furnish information on status of output devices (solenoids and relays). However, status parameters are only an indication that output signals have been sent to devices by control module; they do not indicate if devices have responded properly to signal. Check for proper response at output device using a voltmeter or test light.

If trouble codes are not present, this is not necessarily an indication a problem does not exist. Driveability related problems with codes displayed occur about 20 percent of the time, while driveability problems without codes occur about 80 percent of the time. Sensors that are out of specification WILL NOT set a trouble code but WILL cause driveability problems. Using scan tool is the easiest method of checking sensor specifications and other data parameters. Scan tool is also useful in finding intermittent wiring problems by wiggling wiring harness and connections (key on, engine off) while observing scan tool.

TROUBLE CODE DEFINITIONS

Note. Only transaxle-related trouble codes are listed. For engine-related DTCs, see appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section

1. For 4.6L FWD Cadillac Models, see «TESTS W/CODES»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-control-system-tests-wcodes)
2. For 4.0L Aurora, see «TESTS W/CODES»(ref-20306)

These DTCs pertain to engine performance and must be repaired

first, as engine performance and related component signals

will affect transaxle operation and diagnosis.

PCM TROUBLE CODE DEFINITIONS

HARD OR INTERMITTENT TROUBLE CODE DETERMINATION

During any diagnostic procedure, it must be determined if codes are hard failure codes or intermittent failure codes. Diagnostic tests will not usually help analyze intermittent codes. To determine hard codes and intermittent codes, proceed as follows

1. Enter diagnostic mode. See «RETRIEVING CODES»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e__retrieving-codes) . Read and record all stored DTCs. Exit diagnostic mode and clear trouble codes. See «CLEARING TROUBLE CODES»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e__clearing-trouble-codes) .
2. Apply parking brake and place transaxle in Neutral or Park. Block drive wheels and start engine. MIL should go out. Run warm engine at specified curb idle for 2 minutes and note MIL.
3. If MIL comes on, enter diagnostic mode. Read and record DTCs. This will reveal hard failure codes. DTCs may require a road test to reset hard failure after clearing DTCs. If MIL does not come on, all stored DTCs were intermittent failures.

CLEARING TROUBLE CODES

A scan tool can clear DTCS from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

DIAGNOSTIC TESTS

Note. Proceed to displayed DTC. Not all DTCs are applicable to all models.

Following diagnostic tests are DTC specific. Always perform On-Board Diagnostic (ODD) System Check prior to performing any diagnostic procedure. For terminal locations, see WIRING DIAGRAMS . For engine-related DTCs, see appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section.

1. For 4.6L FWD Cadillac Models, see «TESTS W/CODES»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-control-system-tests-wcodes)
2. For 4.0L Aurora, see «TESTS W/CODES»(ref-20306)

Diagnostic Aids

Diagnostic aids located at end of each diagnostic test, are additional tips used to help diagnose trouble codes when diagnostic procedures do not find a problem.

ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK

Note. Use of Tech 1 scan tool is required to perform OBD system check. Perform this test prior to performing any diagnostic procedures in DTC tests.

The OBD System Check determines

1. If Malfunction Indicator Light (MIL) works.
2. If PCM is operating and can recognize a fault.
3. If any codes are stored.

OBD system check is the starting point for utilizing the self-diagnostic system for determining computer-related problems. After performing necessary tests as described in diagnostic system check, if no codes are indicated and driveability problems still exist, see appropriate H - TEST W/O CODES article in the ENGINE PERFORMANCE section

1. For 4.6L FWD Cadillac Models, see «TESTS W/O CODES»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-control-system-tests-wo-codes)
2. For 4.0L Aurora, see «TESTS W/O CODES»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-control-system-tests-wo-codes)

Note. The following steps should be performed first to reduce diagnostic time and prevent replacement of good parts.

Buick & Oldsmobile

1. Turn ignition on with engine off. Observe Malfunction Indicator Light (MIL). If MIL illuminates, go to next step. If MIL does not illuminate, go to A-1, MIL INOPERATIVE under BASIC TESTING article ENGINE PERFORMANCE section: For 4.6L FWD Cadillac Models, see «BASIC TESTING»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-controls-basic-engine-testing-46l) For 4.0L Aurora, see «BASIC TESTING»(ref-20281)
2. Turn ignition off. Install Tech 1 scan tool and follow scan tool manufacturer's instructions to proceed with test. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to A-4, NO SCAN TOOL DATA under appropriate BASIC TESTING article in the ENGINE PERFORMANCE section.
3. Attempt to start engine. If engine start and runs, go to next step. If engine does not start or starts and dies, go to NO START DIAGNOSIS (A-3) under appropriate BASIC TESTING article in the ENGINE PERFORMANCE section.
4. Using scan tool, observe DTC statuses; MIL REQUEST, FAIL THIS IGN, LAST TST FAIL and HISTORY. If any of these DTC status are present, refer to affected DTC to diagnose problem. If DTC(s) are not present, check related circuit or component(s). See appropriate I - SYSTEM/ COMPONENT TESTS article in the ENGINE PERFORMANCE section: For 4.6L FWD Cadillac Models, see «SYSTEM/COMPONENT TESTS»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) For 4.0L Aurora, see «SYSTEM/COMPONENT TESTS»(ref-20351)

Cadillac

1. Turn ignition on with engine off. Wait about 5 seconds. Observe Malfunction Indicator Light (MIL). If MIL illuminates, go to next step. If MIL does not illuminate, diagnose problem using DTC P1641. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section: For 4.6L FWD Cadillac Models, see «TESTS W/CODES»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-control-system-tests-wcodes) For 4.0L Aurora, see «TESTS W/CODES»(ref-20306)
2. Turn ignition off. Install Tech 1 scan tool and follow scan tool manufacturer's instructions to proceed with test. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to A-4, NO SCAN TOOL DATA under BASIC TESTING article in the ENGINE PERFORMANCE section: For 4.6L FWD Cadillac Models, see «BASIC TESTING»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-controls-basic-engine-testing-46l) For 4.0L Aurora, see «BASIC TESTING»(ref-20281)
3. Using scan tool in MISC TESTS function, select MIL OUTPUT TEST. Command MIL to turn off, using scan tool. If MIL turns off when commanded, go to next step. If MIL does not turn off when commanded, diagnose problem using DTC P1641. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section.
4. Attempt to start engine. If engine start and runs, go to next step. If engine does not start or starts and dies, go to NO START DIAGNOSIS (A-3) under appropriate BASIC TESTING article in the ENGINE PERFORMANCE section.
5. Using scan tool, observe DTC statuses; MIL REQUEST, FAIL THIS IGN, LAST TST FAIL and HISTORY. If any of these DTC status are present, refer to affected DTC to diagnose problem. If DTC(s) are not present, check related circuit or component(s). See appropriate I - SYSTEM/ COMPONENT TESTS article in the ENGINE PERFORMANCE section: For 4.6L FWD Cadillac Models, see «SYSTEM/COMPONENT TESTS»(/cadillac/deville-concours/1994-1998/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-46l) For 4.0L Aurora, see «SYSTEM/COMPONENT TESTS»(ref-20351)

DTC P0218 - TRANSAXLE TEMPERATURE TOO HIGH

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS in section No. 1.

Circuit Description

Transaxle Fluid Temperature (TFT) sensor is a negative coefficient thermistor. When transaxle fluid is cold, sensor resistance is high. As transaxle temperature warms up, sensor resistance lowers. PCM uses TFT information to control Torque Converter Clutch (TCC), line pressure and shift timing. TFT range is from -40 to 305°F (-40 to 151°C). IDLE ENGINE TRANSMISSION HOT message will display on Driver Information Center (DIC).

Conditions For Setting DTC P0218

DTC will set under the following conditions

1. DTCs P0116, P0117 or P0118 (engine coolant temperature) are not present.
2. DTCs P0711, P0712 or P0713 (transaxle fluid temperature) are not present.
3. Transaxle fluid temperature is greater than 266°F (130°C) for 15 minutes, or 291°F (144°C) for 32 seconds.

Diagnostic Procedure

1. Ensure transaxle fluid level is correct. DTC P0218 can only be set if one or more of the following conditions exist. Inspect for these conditions: Engine overheating (thermostat and/or restricted radiator) Vehicle overloading Transaxle fluid contaminated with anti-freeze Transaxle filter clogged or not seated properly Low line pressure (cooler lines clogged or restricted)

Repair or replace components as necessary, then go to next step.

2) After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0218". Turn ignition on for more than 5 seconds. Ensure transaxle fluid temperature stays below 248°F (120°C). If DTC P0218 is not present, repair is complete. If DTC P0218 is still present, repeat test.

Check transaxle and PCM connectors for bent, broken or backed out terminals. Check transaxle cooling system for possible blockage and/or restrictions. Ensure transaxle fluid level is correct.

P0502, VEHICLE SPEED SENSOR CIRCUIT (LOW INPUT)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Vehicle speed is signaled to PCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transaxle case extension. PM generator produces an AC voltage as speed sensor rotor teeth pass sensor's magnetic field. PCM converts AC voltage into digital signal. PCM uses vehicle speed to determine shift timing, TCC apply and release, and gear ratio calculations. VSS voltage will vary from .5 volts AC at 100 RPM to more than 100 volts AC at 8000 RPM. VSS resistance value is 1300-1950 ohms. DTC P0502 is set if PCM detects a low vehicle output speed when vehicle has high engine speed in drive gear.

Conditions For Setting DTC P0502

DTC will set under the following conditions

1. DTCs P0101, P0102 and P0103 (MAF sensor), or P0121, P0122 and P0123 (throttle position) are not present.
2. DTCs P0716 and P0717 (transaxle input shaft speed sensor) and P1810 (TFP valve position switch) are not present.
3. Transaxle is not in Park, Neutral or Reverse.
4. Engine speed is more than 2000 RPM.
5. Throttle angle is more than 12.8 degrees.
6. Vehicle speed is less than 5 MPH for 2 seconds.
7. Engine torque is more than 80 ft. lbs. (109 N.m).

DTC P0502 will be stored in PCM history. MIL will light at first failure signal. SERVICE ENGINE SOON, SPEED SENSOR FAULT is displayed on Driver Information Display (DIC). PCM will inhibit TCC and goes to default line pressure. PCM will calculate vehicle speed from input speed sensor and commanded gear. PCM disables cruise control.

Diagnostic Procedures

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Raise and support vehicle. CAUTION: To prevent damage to drive axles, support lower control arms in normal horizontal position.
2. Start engine and let idle. Shift gear selector to "D" position. Select OSS RPM on scan tool. With drive wheels rotating, if transaxle output speed does not increase when wheel speed increases, go to next step. If transaxle output speed increases when wheel speed increases, cause is intermittent. See DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect PCM connector C2. Connect voltmeter between VSS terminals at PCM connector C2. Rotate drive wheels and observe voltmeter display. If voltage is more than .5 volt, go to next step. If voltage is less than .5 volt, go to step 5.
4. Use scan tool to check for most current PCM calibration I.D. number. Refer to manufacturer service bulletins if necessary. If I.D. number matches, replace PCM, then go to step 8). If I.D number does not match, update PCM with latest calibration, then go to step 8.
5. Connect ohmmeter between VSS terminals at PCM connector C2. If resistance is less than 1950 ohms, go to next step. If resistance is more than 1950 ohms, check for open circuit between VSS and PCM. Repair as necessary, then go to step 8). If open circuit is not found, go to step 7.
6. Check for VSS wires shorted together. Repair wires as necessary, then go to next step. If resistance is more than 1300 ohms, check for short to ground in circuits between VSS and PCM. Repair circuits as necessary, then go to step 8. If wires were not shorted together or shorted to ground, go to next step.
7. Remove VSS from transaxle. Connect ohmmeter between VSS terminals. If resistance is 1300-1950 ohms, replace PCM and go to next step. If resistance is not 1300-1950 ohms, replace VSS, then go to next step.
8. Install VSS into transaxle. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0502". Test drive vehicle. If DTC P0502 is not present, repair is complete. If DTC P0502 is still present, repeat test.

Check for Electromagnetic Interferences (EMI) induced on VSS circuits caused by misrouted wires along spark plug wires. Check for bent, backed out or broken terminals, or misaligned connectors. Ensure VSS is secured to transaxle case extension.

Vehicle speed is signaled to PCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transaxle case extension. PM generator produces an AC voltage as speed sensor rotor teeth pass sensor's magnetic field. PCM converts AC voltage into digital signal. PCM uses vehicle speed to determine shift timing, TCC apply and release, and gear ratio calculations. VSS voltage will vary from .5 volt AC at 100 RPM to more than 100 volts AC at 8000 RPM. VSS resistance value is 1300-1950 ohms. DTC P0502 is set if PCM detects a low vehicle output speed when vehicle has high engine speed in drive gear.

Conditions For Setting DTC P0503

DTC will set under the following conditions

1. DTCs P0101, P0102 and P0103 (MAF sensor), or P0121, P0122 and P0123 (throttle position) are not present.
2. DTCs P0716 and P0717 (transaxle input shaft speed sensor).
3. Ignition on for more than 2 seconds.
4. Gear selection is more than 3 seconds.
5. Engine speed is more than 500 RPM.
6. Throttle angle is more than 12.8 degrees.
7. Traction control is inactive.
8. Engine torque is more than 80 ft. lbs. (109 N.m).
9. Vehicle speed drops more than 11 MPH in .012 seconds and input speed does not drop 100 RPM within .125 seconds, occurring 10 times in 10 seconds.

DTC P0503 will be stored in PCM history. MIL will light. SERVICE ENGINE SOON, SPEED SENSOR FAULT is displayed on Driver Information Display (DIC). PCM will inhibit TCC and goes to default line pressure. PCM will calculate vehicle speed from input speed sensor and commanded gear. PCM disables cruise control.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Raise and support vehicle. CAUTION: To prevent damage to drive axles, support lower control arms in normal horizontal position.
2. Start engine and let idle. Shift gear selector to "D" position. Select OSS RPM on scan tool. With drive wheels rotating, if transaxle output speed does not increase when wheel speed increases, go to next step. If transaxle output speed increases when wheel speed increases, cause is intermittent. See DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect PCM connector C2. Connect voltmeter between VSS terminals at PCM connector C2. Rotate drive wheels and observe voltmeter display. If voltage is more than .5 volt, go to next step. If voltage is less than .5 volt, go to step 5.
4. Use scan tool to check for most current PCM calibration I.D. number. Refer to manufacturer service bulletins if necessary. If I.D. number matches, replace PCM, then go to step 8 If I.D number does not match, update PCM with latest calibration, then go to step 8.
5. Connect ohmmeter between VSS terminals at PCM connector C2. If resistance is less than 1950 ohms, go to next step. If resistance is more than 1950 ohms, check for open circuit between VSS and PCM. Repair as necessary, then go to step 8. If open circuit is not found, go to step 7.
6. Check for VSS wires shorted together. Repair wires as necessary, then go to next step. If resistance is more than 1300 ohms, check for short to ground in circuits between VSS and PCM. Repair circuits as necessary, then go to step 8. If wires were not shorted together or shorted to ground, go to next step.
7. Remove VSS from transaxle. Connect ohmmeter between VSS terminals. If resistance is 1300-1950 ohms, replace PCM and go to next step. If resistance is not 1300-1950 ohms, replace VSS, then go to next step.
8. Install VSS into transaxle. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0503". Test drive vehicle. If DTC P0503 is not present, repair is complete. If DTC P0503 is still present, repeat test.

Check for Electromagnetic Interferences (EMI) induced on VSS circuits caused by misrouted wires along spark plug wires. Check for bent, backed out or broken terminals, or misaligned connectors. Ensure VSS is secured to transaxle case extension.

P0711, TRANS. FLUID TEMPERATURE (TFT) SENSOR CIRCUIT (RANGE/PERFORMANCE)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transaxle Fluid Temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. TFT sensor resistance decreases as transaxle fluid warms. PCM provides a 5 volt reference to sensor on TFT signal circuit. A short to ground in circuit results in low signal voltage. TFT operating range is from -40° to 305°F (-40° to 151°C). DTC P0711 is set when PCM detects an intermittent voltage or no voltage change in TFT sensor circuit.

Conditions For Setting DTC P0711

DTC will set under the following conditions

1. DTC P0116, P0117, P0118, P1114 or P1115 is not present.
2. DTC P0502 or P0503 is not present.
3. DTC P0560 (system voltage malfunction) is not present.
4. DTC P0712 or P0713 is not present.
5. DTC P0716 or P0717 (input speed sensor) is not present.
6. Transaxle fluid temperature is 32-212°F (0-100°C) at start- up.
7. Engine is running for more than 5 minutes.
8. Vehicle speed is more than 5 MPH for 2 minutes.
9. TCC slip is more than 48 RPM for 2 minutes.
10. Engine coolant temperature is more than 32°F (0°C) and has changed more than 72°F (40°C) since start-up.

If any ECT codes are set or ECT is more than 230°F (110°C) and engine run time is more than 5 minutes, PCM will substitute a TFT value of 269°F (132°C).

If ECT is less than 230°F (110°C), PCM will substitute a TFT value of ECT minus 50°F (10°C) when IAT is less than 176°F (80°C) at ignition on. If IAT is more than 176°F (80°C), PCM will substitute a TFT value of ECT plus 50°F (10°C).

If none of these conditions exist, PCM will substitute a TFT value of 176°F (80°C).

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Clear DTCs. Start engine and allow to idle. Monitor TFT, ECT and IAT sensor temperature values. If TFT sensor value is default temperature as described in CONDITIONS FOR SETTING DTC P0711, go to next step. If TFT sensor value is not default temperature as described in CONDITIONS FOR SETTING DTC P0711, go to step 6.
3. Cycle ignition off, and on. Select "TFT Sensor Volts" on scan tool. Wiggle harness and connectors between PCM and transaxle 20-pin connector while observing scan tool. If TFT sensor voltage does not show erratic changes, go to step 5. If TFT sensor voltage shows erratic changes, go to next step.
4. Check TFT sensor circuit between PCM and transaxle 20-pin connector and repair as necessary then go to next step. If circuit is okay, go to next step.
5. Check transaxle harness between transaxle 20-pin connector and TFT sensor and repair as necessary then go to next step. If transaxle harness is okay. See «COMPONENT TESTS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . Check and replace TFT sensor as necessary then go to next step. If TFT sensor is okay, replace PCM then go to next step.
6. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0711". Turn ignition switch to ON position for 15 seconds. If DTC P0711 is not present, repair is complete. If DTC P0711 is still present, repeat test.

Condition may be intermittent. Inspect transaxle and PCM connectors for bent terminals. Check engine and transaxle harness for short to ground. Check transaxle cooling system for possible blockage and/or restrictions.

P0712, TRANS. FLUID TEMPERATURE (TFT) SENSOR CIRCUIT (LOW INPUT)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transaxle Fluid Temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. PCM provides a 5 volt reference to sensor on TFT signal circuit. A high fluid temperature or short to ground in circuit results in low signal voltage. TFT operating range is from -40° to 305°F (-40° to 151°C). DTC P0712 detects a short to ground on TFT sensor circuit.

Conditions For Setting DTC P0712

DTC will set under the following conditions

1. Ignition switch is in ON position.
2. PCM detects a reading of 298°F (148°C) or more for 5 seconds.

If any ECT codes are set or ECT is more than 230°F (110°C) and engine run time is more than 5 minutes, PCM will substitute a TFT value of 269°F (132°C).

If ECT is less than 230°F (110°C), PCM will substitute a TFT value of ECT minus 50°F (10°C) when IAT is less than 176°F (80°C) at ignition on. If IAT is more than 176°F (80°C), PCM will substitute a TFT value of ECT plus 50°F (10°C).

If none of these conditions exist, PCM will substitute a TFT value of 176°F (80°C).

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TFT sensor volts" on scan tool. If TFT voltage is less than or equal to.08 volt, go to next step. If TFT voltage is more than.08 volt, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect transaxle 20-pin harness connector. Turn ignition switch to ON position. DO NOT start engine. If TFT voltage is less than 4.8 volts, go to step 5. If TFT voltage is more than 4.8 volts, install Jumper Harness (J-39775) on transmission side of 20-pin connector.
4. Using a DVOM, measure resistance between terminal "M" and ground. (Scheme 67) If resistance is more than 100 ohms, go to step 7. If resistance is less than 100 ohms, go to step 6.
5. Check for short to ground in TFT sensor high circuit between PCM and 20-pin transaxle connector. Repair wire as necessary, then go to step 7. If circuit is okay, replace PCM then go to step 7.
6. Check for short to ground in TFT sensor high circuit between PCM and TFT sensor. Repair circuit as necessary, then go to next step. If circuit is okay, replace TFT sensor then go to next step.
7. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Start engine and select "TFT sensor volts" on scan tool. Ensure TFT voltage is more than.08 volt for 5 seconds. Select "Specific DTC" and enter DTC "P0712". Turn ignition switch to ON position for 15 seconds. If DTC P0712 is not present, repair is complete. If DTC P0712 is still present, repeat test.

Condition may be intermittent. Inspect transaxle and PCM connectors for bent terminals. Check engine and transaxle harness for short to ground. Check transaxle cooling system for possible blockage and/or restrictions.

P0713, TRANS. FLUID TEMPERATURE (TFT) SENSOR CIRCUIT (HIGH INPUT)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transaxle Fluid Temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. PCM provides a 5 volt reference to sensor on TFT signal circuit. An open in circuits or low fluid temperature result in high signal voltage. TFT operating range is from -40° to 305°F (-40° to 151°C). DTC P0713 detects a continuous open or short to power on TFT sensor circuit.

Conditions For Setting DTC P0713

DTC will set under the following conditions

1. DTC P0117 or P0118 is not present.
2. PCM detects a reading of -40°F (-40°C) or less (5.04 volts or more) for 6 seconds.
3. Vehicle speed is more than 10 MPH for 5 minutes.
4. ECT is more than -13°F (-25°C).

If any ECT codes are set or ECT is more than 230°F (110°C) and engine run time is more than 5 minutes, PCM will substitute a TFT value of 269°F (132°C).

If ECT is less than 230°F (110°C), PCM will substitute a TFT value of ECT minus 50°F (10°C) when IAT is less than 176°F (80°C) at ignition on. If IAT is more than 176°F (80°C), PCM will substitute a TFT value of ECT plus 50°F (10°C).

If none of these conditions exist, PCM will substitute a TFT value of 176°F (80°C).

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TFT sensor volts" on scan tool. If TFT voltage is more than or equal to 4.98 volts, go to next step. If TFT voltage is less than 4.98 volts, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect transaxle 20-pin harness connector. Connect fused jumper wire between transaxle 20-pin harness connector terminal "M" (PCM side of harness) and transaxle case. Turn ignition switch to ON position. DO NOT start engine. If TFT voltage is more than or equal to 4.98 volts, go to next step. If TFT voltage is less than 4.98 volts, go to step 6.
4. Check for open in TFT sensor high circuit between PCM and 20-pin transaxle connector. Repair wire as necessary, then go to step 7. If circuit is okay, go to next step.
5. Check for open in TFT sensor low circuit between PCM and 20-pin transaxle connector. Repair wire as necessary, then go to step 7. If circuit is okay, replace PCM then go to next step.
6. Check for open in TFT sensor high and low circuits between 20-pin transaxle connector (transaxle side of harness) and TFT sensor. Repair wire(s) as necessary, then go to next step. If circuits are okay, replace TFT sensor, then go to next step.
7. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Road test vehicle. Ensure vehicle speed is more than 10 MPH for 5 minutes. Select "Specific DTC" and enter DTC "P0713". Start engine and run for 15 seconds. If DTC P0713 is not present, repair is complete. If DTC P0713 is still present, repeat test.

Condition may be intermittent. Inspect transaxle and PCM connectors for bent or backed out terminals.

P0716, INPUT SPEED SENSOR CIRCUIT (RANGE/PERFORMANCE MALFUNCTION)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transmission input speed sensor consists of a permanent magnet surrounded by a coil of wire. Rotation of input shaft drive sprocket housing induces an AC voltage in circuit. Signal voltage and frequency vary directly with input shaft drive sprocket rotational speed. Input speed sensor has a resistance of 1300-1950 ohms. P0716 detects an unrealistically large change in input speed.

Conditions For Setting DTC P0716

DTC will set under the following conditions

1. DTCs P0121, P0122 or P0123 (throttle position sensor) are not present.
2. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
3. DTC P0717 (input speed sensor signal) is not present.
4. DTCs P0751 or P0753 (1-2 shift solenoid) are not present.
5. DTCs P0756 or P0758 (2-3 shift solenoid) are not present.
6. Vehicle speed is more than 7 MPH.
7. Throttle angle is more than 12.8 degrees.
8. Engine is running for 5 seconds and not in fuel cutoff.
9. Input speed varies by 1000 RPM for more than .075 seconds, occurring 10 times in 10 seconds.

DTC P0716 will be stored in PCM history. MIL will light and SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM will freeze shift adapts from being updated and sets line pressure to default. PCM inhibits TCC apply. PCM calculates vehicle speed from vehicle speed and command gear.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "Trans ISS" on scan tool. Start engine. If ISS RPM is less than or equal to 100 RPM, go to next step. If ISS RPM is more than 100 RPM, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect PCM connector C1. Using DVOM, measure voltage between ISS sensor high and low circuit terminals at PCM connector C1 while cranking engine. If voltage is more than.5 volt, replace PCM, then go to step 12. If voltage is less than.5 volt, go to next step.
4. Turn ignition off. Reconnect PCM connector C1. Disconnect transaxle 20-pin harness connector. Connect DVOM between transaxle 20-pin harness connector terminal "S" (PCM side of harness) and ground. (Scheme 67) Turn ignition on. If voltage is less than 300 mV, go to next step. If voltage is more than 300 mV, go to step 6.
5. Check ISS sensor high circuit for open or short to ground between PCM and transaxle 20-pin harness connector. Repair wire as necessary, then go to step 12. If circuit is okay, replace PCM then go to step 12.
6. Connect test light between transaxle 20-pin harness connector terminal "E" and terminal "V". If test light does not glow, go to step 8. If test light glows, go to next step.
7. Check ISS sensor low circuit for open between PCM and transaxle 20-pin harness connector. Repair wire as necessary, then go to step 12. If circuit is okay, replace PCM then go to step 12.
8. Turn ignition off. Install Jumper Harness (J-39775) on transmission side of 20-pin connector. Using a DVOM, measure resistance between terminal "S" and terminal "V". If resistance is 1300-1950 ohms, go to step 11. If resistance is less than 1300 ohms, go to step 10). If resistance is more than 1950 ohms, go to next step.
9. Check for open in ISS sensor high and low circuits between 20-pin transaxle connector (transaxle side of harness) and ISS sensor. Repair wire(s) as necessary, then go to step 12. If circuits are okay, replace ISS sensor, then go to step 12.
10. Check for short between ISS sensor high and low circuits between 20-pin transaxle connector (transaxle side of harness) and ISS sensor. Repair wire(s) as necessary, then go to step 12. If circuits are okay, replace ISS sensor, then go to step 12.
11. Using a DVOM, measure resistance between transaxle 20-pin harness connector terminal "A" (transaxle side of harness) and ground. If resistance is 100 ohms or more, problem is intermittent, see DIAGNOSTIC AIDS then go to next step. If resistance is less than 100 ohms, replace transaxle harness then go to next step.
12. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Road test vehicle with throttle angle more than 13 degrees and more than 7 MPH. Select "Specific DTC" and enter DTC "P0716". If DTC P0716 is not present, repair is complete. If DTC P0716 is still present, repeat test.

Inspect wiring for poor connections at PCM and at transmission 20-pin connector. Check for possible bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for possible intermittent short or open condition, move wiring harness while observing scan tool for value change.

P0717, INPUT SPEED SENSOR CIRCUIT (NO SIGNAL)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transmission input speed sensor consists of a permanent magnet surrounded by a coil of wire. Rotation of input shaft drive sprocket housing induces an AC voltage in circuit. Signal voltage and frequency vary directly with input shaft drive sprocket rotational speed. Input speed sensor has a resistance of 1300-1950 ohms. P0717 detects a low input speed while vehicle and engine speed is high.

Conditions For Setting DTC P0717

DTC will set under the following conditions

1. DTCs P0121, P0122 or P0123 (throttle position sensor) are not present.
2. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
3. DTC P1810 (TFP valve position switch) is not present.
4. Vehicle speed is more than 10 MPH.
5. Engine is running for 5 seconds
6. Transmission is not in Park or Neutral.
7. Measured input speed is less than 50 RPM for at least 2 seconds.

DTC P0717 will be stored in PCM history. MIL will light and SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM will freeze shift adapts from being updated and sets line pressure to default. PCM inhibits TCC apply. PCM calculates vehicle speed from vehicle speed and command gear.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "Trans ISS" on scan tool. Start engine. If ISS RPM is less than or equal to 100 RPM, go to next step. If ISS RPM is more than 100 RPM, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect PCM connector C1. Using DVOM, measure voltage between ISS sensor high and low circuit terminals at PCM connector C1 while cranking engine. If voltage is more than.5 volt, replace PCM, then go to step 12. If voltage is.5 volt or less, go to next step.
4. Turn ignition off. Reconnect PCM connector C1. Disconnect transaxle 20-pin harness connector. Connect DVOM between transaxle 20-pin harness connector terminal "S" (PCM side of harness) and ground. (Scheme 67) Turn ignition on. If voltage is less than 300 mV, go to next step. If voltage is more than 300 mV, go to step 6.
5. Check ISS sensor high circuit for open or short to ground between PCM and transaxle 20-pin harness connector. Repair wire as necessary, then go to step 12. If circuit is okay, replace PCM then go to step 12.
6. Connect test light between transaxle 20-pin harness connector terminal "E" and terminal "V". If test light does not glow, go to step 8. If test light glows, go to next step.
7. Check ISS sensor low circuit for open between PCM and transaxle 20-pin harness connector. Repair wire as necessary, then go to step 12. If circuit is okay, replace PCM then go to step 12.
8. Turn ignition off. Install Jumper Harness (J-39775) on transmission side of 20-pin connector. Using a DVOM, measure resistance between terminal "S" and terminal "V". If resistance is 1300-1950 ohms, go to step 11. If resistance is less than 1300 ohms, go to step 10. If resistance is more than 1950 ohms, go to next step.
9. Check for open in ISS sensor high and low circuits between 20-pin transaxle connector (transaxle side of harness) and ISS sensor. Repair wire(s) as necessary, then go to step 12. If circuits are okay, replace ISS sensor, then go to step 12.
10. Check for short between ISS sensor high and low circuits between 20-pin transaxle connector (transaxle side of harness) and ISS sensor. Repair wire(s) as necessary, then go to step 12. If circuits are okay, replace ISS sensor, then go to step 12.
11. Using a DVOM, measure resistance between transaxle 20-pin harness connector terminal "A" (transaxle side of harness) and ground. If resistance is 100 ohms or more, problem is intermittent, see DIAGNOSTIC AIDS then go to next step. If resistance is less than 100 ohms, replace transaxle harness then go to next step.
12. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Start engine. Ensure ISS is more than 50 RPM. Select specific DTC" and enter DTC "P0717". If DTC P0717 is not present, repair is complete. If DTC P0717 is still present, repeat test.

Inspect wiring for poor connections at PCM and at transmission 20-pin connector. Check for possible bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for possible intermittent short or open condition, move wiring harness while observing scan tool for value change.

P0719, TCC BRAKE SWITCH CIRCUIT LOW INPUT (SWITCH STUCK ON)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) brake switch is used to indicate brake pedal status to PCM. DTC P0719 detects a status change in brakelight switch and extended travel brake switch input without status change of TCC brake switch input.

Conditions For Setting DTC P0719

DTC will set under the following conditions

1. P0502 or P0503 (vehicle speed sensor) are not present.
2. P1602 (loss of PCM serial data) is not present.
3. TCC brake switch input is zero volt.
4. Traction control and ABS are not active.
5. Vehicle speed and wheel sensor speed are within 6 MPH.

The following conditions must occur 7 times within 15 minutes without status change of TCC brake input

1. Vehicle speed is less than 5 MPH.
2. Vehicle takes more than 2.5 seconds to accelerate to 20 MPH, then vehicle speed remains above 20 MPH for at least 6 seconds.

For TCC operation, PCM will use extended travel brake switch or brakelight switch input. SERVICE ELECTRICAL SYSTEM will display no Drivers Information Center (DIC).

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTCs P1574 or P1575 are also present, remove and inspect brake circuit fuse. See «WIRING DIAGRAMS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . If fuse is open, check for short to ground in brake switch circuits to fuse. Repair circuit as necessary, then go to step 4. Replace fuse. If DTCs are not present, go to next step.
3. Select "TCC Brake Switch" on scan tool. Disconnect TCC brake switch. Connect fused jumper wire between brake switch connector terminals. If brake switch status on scan tool changes from applied to released, replace TCC brake switch, then go to next step. If brake switch status on scan tool does not change, check for open in brake switch input circuit. Repair circuit as necessary, then go to next step. If circuit is okay, replace PCM, then go to next step.
4. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0719". Turn ignition switch to ON position. If DTC P0719 is not present, repair is complete. If DTC P0719 is still present, repeat test.

Check TCC brake switch for proper adjustment. Check PCM calibration for current update. Inspect brake switch and PCM connectors for bent, backed out or broken terminals.

P0724, BRAKE SWITCH CIRCUIT HIGH INPUT (SWITCH STUCK OFF)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) brake switch is used to indicate brake pedal status to PCM. DTC P0724 detects an status change in brakelight switch and extended travel brake switch input without status change of TCC brake switch input.

Conditions For Setting DTC P0724

DTC will set under the following conditions

1. P0502 or P0503 (vehicle speed sensor) are not present.
2. P1574 and P1575 (extended travel and brakelight switch) are not present.
3. P1602 (loss of PCM serial data) is not present.
4. TCC brake switch input is ignition voltage.
5. Traction control and ABS are not active.
6. Vehicle speed and wheel sensor speed are within 6 MPH.

The following conditions must occur 7 times within 15 minutes without status change of TCC brake input

1. Vehicle speed is less than 5 MPH.
2. Vehicle takes more than 2.5 seconds to accelerate to 20 MPH, then vehicle speed remains above 20 MPH for at least 6 seconds.

For TCC operation, PCM will use extended travel brake switch or brakelight switch input. SERVICE ELECTRICAL SYSTEM will display on Drivers Information Center (DIC).

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TCC Brake Switch" on scan tool. Disconnect TCC brake switch connector. If brake switch status on scan tool changed from released to applied, replace TCC brake switch, then go to next step. If brake switch status on scan tool does not change, check for short to voltage in brake switch input circuit. Repair circuit as necessary, then go to next step. If circuit is okay, replace PCM, then go to next step.
3. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Turn ignition switch to ON position for 15 seconds. Apply brakes for 2 seconds. Select "Specific DTC" and enter DTC "P0724". If DTC P0724 is not present, repair is complete. If DTC P0724 is still present, repeat test.

Check TCC brake switch for proper adjustment. Check PCM calibration for current update. Inspect brake switch and PCM connectors for bent, backed out or broken terminals.

P0730, INCORRECT GEAR RATIO

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS.

PCM calculates gear ratio from input and out speed sensors. PCM compares known gear ratio to calculated ratio for each gear selected. DTC P0730 detects steady state adapts at maximum and incorrect gear ratio due to excessive transaxle slip.

Conditions For Setting DTC P0730

DTC will set under the following conditions

1. DTCs P0101, P0102 and P0103 (MAF sensor), or P0121, P0122 and P0123 (throttle position) are not present.
2. DTCs P0716 and P0717 (transaxle input shaft speed sensor) and P1810 (TFP valve position switch) are not present.
3. Transaxle is not in Park or Neutral.
4. DTCs P0753 (1-2 shift solenoid) are not present.
5. DTCs P0758 (2-3 shift solenoid) are not present.
6. Vehicle speed is more than 7 MPH.
7. Throttle angle is more than 15.7 degrees.
8. Engine is running for 5 seconds.
9. One or more steady state cell at maximum.
10. TFT is more than 68°F (20°C).
11. Torque is more than 100 ft. lbs. (135 N.m).

The following conditions must occur for 4 seconds

1. 1st gear ratio is less than 2.87 or more than 3.11.
2. 2nd gear ratio is less than 1.54 or more than 1.71.
3. 3rd gear ratio is less than .95 or more than 1.05.
4. 4th gear ratio is less than .65 or more than .71.
5. Reverse gear ratio is less than 2.02 or more than 2.23.

"SERVICE TRANSMISSION" will be displayed on Drivers Information Center (DIC). PCM will command maximum line pressure. All adapts will be disabled. Torque management will be inhibited.

1. Ensure fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. If DTCs P0502, P0503, P0716, P0717, P0753 or P0758 are set, repair these DTCs first then go to step 22). If DTCs P0502, P0503, P0716, P0717, P0753 or P0758 are not set, go to next step.
2. Connect oil pressure gauge to line pressure test port, see HYDRAULIC PRESSURE TESTS in HYDRA-MATIC 4T80-E overhaul article. Select "PC Sol" on scan tool. Start engine and allow to idle in Park position. Increase and decrease PC solenoid valve amperage. If line pressure and amperage are 50-220 psi/.1-1.1 amps, go to next step. If line pressure and amperage are more than 50-220 psi/.1-1.1 amps, inspect and repair PC solenoid valve, see COMPONENT TESTS. If line pressure and amperage are less than 50-220 psi/.1-1.1 amps, inspect and repair following: Scavenge pump leaking at pump body. Scavenge tube restriction. Scavenge tube seals damaged or leaking. Primary pump leaking at gasket or pump body. Clogged screens. Pressure relief valve stuck. Secondary pump leaking at gasket or pump body.

See COMPONENT DISASSEMBLY & REASSEMBLY in AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E article, then go to step 22.

Note. All TFP position switch range status will be given in A/B/C order (Example: ON/OFF/ON).

1. 3) Select snap shot mode on scan tool and capture "TFP Val Position Sw", transaxle gear ratio and commanded gear. Drive vehicle in reverse. If TFP position switch parameters are On/On/Off with a gear ratio of 2.22 or 2.02, repair valve body hydraulic problem then go to step 22. See «AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-overhaul-testing-4t80-e) article. If TFP position switch parameters are not On/On/Off with a gear ratio of more than 2.22 or less than 2.02, go to next step.
2. 4) Drive vehicle in OD and ensure vehicle reaches 4th gear. If TFP position switch parameters are Off/On/On with a gear ratio of less than .65, inspect and repair VSS and ISS circuits. See DTCs P0502, P0503, P0716 and P0717, then go to step 22). If TFP position switch parameters are not Off/On/On with a gear ratio of less than .65, go to next step.
3. 5) If TFP position switch parameters are Off/On/On with a gear ratio of more than 1.05, inspect and repair 3rd clutch, forward clutch and forward clutch sprag, then go to step 22. If TFP position switch parameters are not Off/On/On with a gear ratio of more than 1.05, go to next step.
4. 6) If TFP position switch parameters are On/Off/Off with a gear ratio of more than 1.71, inspect and repair 2nd clutch, 2nd sprag clutch, forward clutch and forward sprag clutch. If TFP position switch parameters are not On/Off/Off with a gear ratio of more than 1.71, go to next step.
5. 7) If TFP position switch parameters are On/Off/Off with a gear ratio of less than 1.54, inspect and repair 3rd clutch, forward clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/Off/Off with a gear ratio of more than 1.71, go to next step.
6. 8) If TFP position switch parameters are On/Off/Off with a gear ratio of less than 2.87, inspect and repair 2nd clutch, 2nd sprag clutch, forward clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/Off/Off with a gear ratio of less than 2.87, go to next step.
7. 9) Drive vehicle in 3rd gear. If TFP position switch parameters are On/On/Off with a gear ratio of less than .95, inspect and repair valve body hydraulic problem and a clutch not releasing then go to step 22. If TFP position switch parameters are not On/On/Off with a gear ratio of less than .95, go to next step.
8. 10) If TFP position switch parameters are On/On/Off with a gear ratio of less than .95 and more than .71, inspect and repair 4th band, 3rd clutch, 4th clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/On/Off with a gear ratio of less than .95 and more than .71, go to next step.
9. 11) If TFP position switch parameters are On/On/Off with a gear ratio of more than 1.05, inspect and repair 3rd clutch, forward clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/On/Off with a gear ratio of more than 1.05, go to next step.
10. 12) If TFP position switch parameters are On/On/Off with a gear ratio of more than 1.71 inspect and repair 2nd clutch, forward clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/On/Off with a gear ratio of more than 1.71, go to next step.
11. 13) If TFP position switch parameters are On/On/Off with a gear ratio of less than 1.54, inspect and repair 3rd clutch, forward clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/On/Off with a gear ratio of less than 1.54, go to next step.
12. 14) If TFP position switch parameters are On/On/Off with a gear ratio of less than 2.87, inspect and repair 2nd clutch, 2nd sprag clutch, forward clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/On/Off with a gear ratio of more than 2.87, go to next step.
13. 15) Drive vehicle in 2nd gear. If TFP position switch parameters are On/On/On with a gear ratio of less than 1.54, inspect and repair valve body hydraulic problem and a clutch not releasing then go to step 22. If TFP position switch parameters are not On/On/On with a gear ratio of less than 1.54, go to next step.
14. 16) If TFP position switch parameters are On/On/On with a gear ratio of more than 1.05, inspect and repair 3rd clutch, forward clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/On/On with a gear ratio of more than 1.05, go to next step.
15. 17) If TFP position switch parameters are On/On/On with a gear ratio of more than 1.71, inspect and repair 2nd clutch, 2nd sprag clutch, forward clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/On/Off with a gear ratio of more than 1.71, go to next step.
16. 18) If TFP position switch parameters are On/On/On with a gear ratio of less than 1.54, inspect and repair 3rd clutch, forward clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/On/On with a gear ratio of less than 1.54, go to next step.
17. 19) If TFP position switch parameters are On/On/On with a gear ratio of less than 2.87, inspect and repair 2nd clutch, 2nd sprag clutch, forward clutch and forward sprag clutch then go to step 22. If TFP position switch parameters are not On/On/On with a gear ratio of less than 2.87, go to next step.
18. 20) Drive vehicle in 1st gear. If TFP position switch parameters are Off/On/On with a gear ratio of less than 2.87, inspect and repair valve body hydraulic problem and a clutch not releasing then go to step 22. If TFP position switch parameters are not Off/On/On with a gear ratio of less than 2.87, go to next step.
19. 21) If TFP position switch parameters are Off/On/On with a gear ratio of less than 3.11, inspect and repair forward clutch, forward sprag clutch and lo roller clutch then go to step 22. If TFP position switch parameters are not Off/On/On with a gear ratio of less than 3.11, replace PCM then go to next step.
20. 22) After repair is complete, select DTC on scan tool. Select "Clear Info" function. Road vehicle in all gears. With vehicle in OD accelerate with throttle angle more than 16 degrees. Engine torque must be more than 100 ft. lbs. (135 N.m). Select "Specific DTC" and enter DTC "P0730". If DTC P0730 is not present, repair is complete. If DTC P0730 is still present, repeat test.

P0741, TCC STUCK OFF

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS.

Torque Converter Clutch (TCC) Pulse Width Modulated (PWM) solenoid controls fluid for TCC apply and release. PCM commands solenoid on and off through ground circuit. When TCC PWM solenoid is de-energized, solenoid will release fluid and release TCC. DTC P0741 detects a high torque converter slip when TCC is commanded on.

Conditions For Setting DTC P0741

DTC will set under the following conditions

1. DTC P0101, P0102 or P0103 (MAF sensor) is not present.
2. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTC P0716 or P0717 (input speed sensor) is not present.
5. DTC P0742 (TCC stuck on) is not present.
6. DTC P1810 (TFP position switch) is not present.
7. DTC P1860 (TCC PWM solenoid) is not present.
8. Throttle angle is more than 8 degrees.
9. Engine must be running for at least 5 seconds.
10. Gear ratio must indicate 2nd, 3rd or 4th gear.
11. TFP position switch must is not in Park or Neutral.
12. Fluid temperature must be 68-248°F (20-120°C).
13. TCC slip speed does not exceed torque limits.
14. Delivered torque is 32-150 ft. lbs. (43-202 N.m).
15. Not in fuel shut off mode.
16. TCC solenoid valve is commanded on at maximum duty cycle.

DTC P0741 will be stored in PCM history. MIL will light at first failure signal. SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM inhibits TCC engagement and 4th gear.

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Repair DTC P0719 first.
2. Drive vehicle at 45 MPH. Select "Output Test". Select "TCC Ena Sol.". Command TCC enable solenoid on. Monitor TCC slip. If TCC slip is -10-67 RPM, see DIAGNOSTIC AIDS. If TCC slip is not -10-67 RPM, check and repair following then go to next step. See HYDRA-MATIC 4T80-E overhaul article: TCC control valve, regulator valve or feed valve are stuck off. Oil pressure screen plugged. TCC solenoid "O" ring is leaking or cut. Turbine shaft seals are cut or worn. TCC for ballooning.
3. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Drive vehicle in D4. Ensure TCC applies for more than 5 seconds. Select "Specific DTC" and enter DTC "P0741". If DTC P0741 is not present, repair is complete. If DTC P0741 is still present, repeat test.

Ensure transaxle fluid level is correct. Transaxle may be in hot mode. Inspect transaxle cooler lines for being pinched, plugged or twisted.

Inspect wiring for poor connections at PCM and at transmission 20-pin connector. Check for possible bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for possible intermittent short or open condition, move wiring harness while observing scan tool for value change.

P0742, TCC CIRCUIT INOPERATIVE (STUCK ON)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS.

Torque Converter Clutch (TCC) solenoid controls hydraulic fluid for TCC apply and release. Under vehicle acceleration TCC is disengaged. DTC P0742 will set when PCM detects TCC slip from -5 RPM to 67 RPM.

Conditions For Setting DTC P0742

DTC will set under the following conditions

1. DTC P0101, P0102 or P0103 (MAF sensor) is not present.
2. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTC P0716 or P0717 (input speed sensor) is not present.
5. DTC P0741 (TCC stuck off) is not present.
6. DTC P1810 (TFP position switch) is not present.
7. DTC P1860 (TCC PWM solenoid) is not present.
8. Throttle angle is more than 11.8 degrees.
9. Engine must be running for at least 5 seconds.
10. TCC solenoid valve is commanded off by PCM.
11. TFP position switch indicates D4.
12. Transaxle gear ratio indicates 2nd, 3rd or 4th gear.
13. Delivered torque is 100-200 ft. lbs. (135-270 N.m).
14. TCC slip speed is from -5 RPM to 67 RPM 3 times for 6.4 seconds.

MIL will light. SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM inhibits TCC engagement and 4th gear if transaxle is in hot mode.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTC P0742 did not set in 6.4 seconds, see DIAGNOSTIC AIDS. If DTC P0742 set in 6.4 seconds, inspect and repair TCC PWM solenoid valve or TCC feed valve. Components may be stuck on due to sediment. Refer to HYDRA-MATIC 4T80-E overhaul article.
3. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Road test vehicle. TCC slip must be less than -5 RPM and more than 67 RPM for 6.4 seconds. Select "Specific DTC" and enter DTC "P0742". If DTC P0742 is not present, repair is complete. If DTC P0742 is still present, repeat test.

Check for DTC P0705 (transaxle range switch). This DTC will affect transaxle operation and may cause a false DTC P0742. Inspect transaxle fluid for sediment or debris.

P0748, PRESSURE CONTROL SOLENOID (PCS) (VALVE CIRCUIT ELECTRICAL PROBLEM)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Pressure Control Solenoid (PCS) valve regulates feed fluid for torque signal pressure. PCM uses Pulse Width Modulated (PWM) signal to regulate torque signal pressure. PCM varies current to PCS valve from .1-1.1 amps.

Conditions For Setting DTC P0748

DTC will set under the following conditions

1. DTC P0560 (system voltage malfunction) is not present.
2. DTC P0730 (incorrect gear ratio) is not present.
3. DTC P1811 (maximum adapt and long shift) is not present.
4. Engine has been running for more than 1 second.
5. Difference between actual PCS valve current draw and commanded current draw .05 amps or more for 2 seconds.

SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM will inhibit torque management. PCM will command maximum line pressure. PCM will disable adapts.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Start engine. Select "A/T outputs PC sol" on scan tool. Apply current from .1-1.1 amps at different settings. If PCS differs from command current by more than .05 amps, go to next step. If PCS does not differ from command current by more than .05 amps, see DIAGNOSTIC AIDS.
2. Turn ignition off. Disconnect transaxle 20-pin harness connector. Install Transaxle Jumper (J-39775) to transaxle side of transaxle 20-pin harness connector. Connect DVOM between terminal "C" and terminal "D". If resistance is 3-8 ohms, go to next step. If resistance is more than 8 ohms, inspect and repair PC solenoid circuits of transaxle harness for an open then go to step 5. If resistance is less than 3 ohms, inspect and repair PC solenoid circuits of transaxle harness for being shorted together then go to step 5. If circuits are okay, replace PCS valve.
3. Connect DVOM between terminal "D" and transaxle case. If resistance is less than 10 ohms, inspect and repair PC solenoid circuits of transaxle harness for a short to ground then go to step 5. If resistance is more than 10 ohms, go to next step. If circuits are okay, replace PCS valve.
4. Disconnect transaxle jumper from transaxle 20-pin harness connector. Reconnect transaxle 20-pin harness connector. Disconnect PCM connector C1. Connect DVOM between terminal No. 38 of PCM connector C1 (PC sol valve low control circuit) and ground. If resistance is more than 10 ohms, inspect and repair PC solenoid circuits of transaxle harness for an open then go to next step. If resistance is less than 10 ohms, inspect and repair PC solenoid circuits of transaxle harness for a short to ground then go to next step. If circuits are okay, replace PCM.
5. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Start engine and run for at least 30 seconds. Select "Specific DTC" and enter DTC "P0748". If DTC P0748 is not present, repair is complete. If DTC P0748 is still present, repeat test.

Inspect PCM, transaxle and PCS solenoid valve connectors for bent, broken or backed out terminals. Ensure transaxle fluid level is correct.

P0751, 1-2 SHIFT SOLENOID ("A") (PERFORMANCE PROBLEM)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS.

PCM identifies a shift solenoid "A" problem by monitoring commanded gear and speed ratio. DTC P0751 will set if PCM detects a gear ratio outside limits for commanded gear.

Conditions For Setting DTC P0751

DTC will set under the following conditions

1. DTC P0101, P0102 or P0103 (MAF sensor) is not present.
2. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTC P0716 or P0717 (input speed sensor) is not present.
5. DTCs P0753 (shift solenoid "A" electrical problem) or DTC P0758 (shift solenoid "B" electrical problem) are not present.
6. DTC P1810 (transmission fluid pressure switch) is not present.
7. Engine has been running for 5 seconds.
8. Vehicle speed is more than 4 MPH.
9. Vehicle is not in fuel shut off mode.
10. Transaxle temperature is more than 86°F (30°C).
11. Transaxle shift is not in progress.
12. Throttle angle is more than 11 degrees.
13. Transmission fluid pressure manual valve position switch indicates D1, D2, D3 or D4.

DTC P0751 will be stored in PCM history and MIL will light. SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM will command 2nd gear and default line pressure. PCM disables state and shift adapts. PCM inhibits TCC and torque management. DTC has 4 different failure criteria. These criteria are as follows

Criteria No. 1

1st gear is commanded. Gear ratio is 1.54-1.71 for one second. Delivered torque is more than 60 lbs. (82 N.m).

Criteria No. 2

2nd gear is commanded. Gear ratio is 2.87-3.11 for 3 seconds. Delivered torque is more than 70 lbs. (96 N.m).

Criteria No. 3

3rd gear is commanded. Gear ratio is .65-.71 for 3 seconds. Delivered torque is more than 60 lbs. (82 N.m).

Criteria No. 4

4th gear is commanded. Gear ratio is .95-1.05 for 5 seconds. Delivered torque is more than 70 lbs. (96 N.m).

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "A/T Output" then select "Shift Trans". Monitor current gear and ratio data pairs. Accelerate vehicle and command 1st gear. If gear ratio is not 1.54-1.71, go to next step. If gear ratio is 1.54-1.71, inspect and repair the following, see «AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-overhaul-testing-4t80-e) article then go to step 6: Lo/Reverse servo apply pin. 1-2 shift valve stuck in upshift position. Forward and/or coast clutch support seals or studs are damaged. Lo roller clutch worn or damaged. Forward clutch piston or seals damaged. Support housing seal rings. Forward sprag. Check ball missing or stuck.
3. Accelerate vehicle and command 3-4 shift. If gear ratio is not .95-1.05, go to next step. If gear ratio is .95-1.05, inspect and repair the following, see «AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-overhaul-testing-4t80-e) article then go to step 6: 1-2 shift solenoid valve for debris. 4th band and servo. 3-4 shift valve bore plug is misassembled.
4. Accelerate vehicle and command 1-2 shift. If gear ratio is not 2.87-3.11 go to next step. If gear ratio is 2.87-3.11, inspect and repair the following, see «AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-overhaul-testing-4t80-e) article then go to step 6: 1-2 shift solenoid valve for debris. Clutches burnt. 1-2 shift valve stuck in 1st gear. 2nd clutch piston, seals or return spring damaged. 2nd sprag not holding. Check ball missing or stuck.
5. Accelerate vehicle and command 2-3 shift. If gear ratio is not .65-.71, see DIAGNOSTIC AIDS. If gear ratio is .65-.71, inspect and repair the following, see «AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-overhaul-testing-4t80-e) article then go to next step: 1-2 shift solenoid valve for debris. Exhaust valve cup plug for driven support or valve installed incorrectly. 3rd clutch plates burnt or damaged. 3rd clutch piston or seals damaged. Check ball missing or stuck.
6. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Test drive vehicle. Ensure transaxle upshifts and downshifts correctly. Select "Specific DTC" and enter DTC "P0751". If DTC P0751 is not present, repair is complete. If DTC P0751 is still present, see «COMPONENT TESTS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) .

Check for DTC P0705 (transaxle range switch). This DTC will affect transaxle upshifts and may cause a false DTC P0751. Inspect transaxle fluid for sediment or debris.

P0753, 1-2 SHIFT SOLENOID ("A") (ELECTRICAL PROBLEM)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

1-2 shift solenoid is used to control transaxle fluid to 1-2 shift valve. Ignition voltage is provided to solenoid through fused circuit. See WIRING DIAGRAMS . Ground is provided by Output Driver Module (ODM) within PCM. PCM monitors voltage levels at ODM. When 1-2 shift solenoid is commanded on, PCM will detect low voltage. When 1-2 shift solenoid is commanded off, PCM will detect high voltage. DTC P0753 will set if voltage limits do not meet calibration at anytime.

Conditions For Setting DTC P0753

DTC will set under the following conditions

1. DTC P1650 (ODM) is not present.
2. Engine has been running for more than 5 seconds.
3. PCM detects a circuit problem on 1-2 shift solenoid valve circuits in 5 seconds.

DTC P0753 will be stored in PCM history and MIL will light. SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM will command 2nd gear and default line pressure. PCM disables state and shift adapts. PCM inhibits TCC and torque management.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. If DTCs P0758 or P1860 are present, go to next step. If DTCs P0758 or P1860 are not present, go to step 3.
2. Remove and inspect appropriate fuse. See «WIRING DIAGRAMS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . Replace fuse if necessary. If fuse is blown, check for short to ground in circuit between fuse and transaxle 20-pin harness connector. If fuse is okay, check for open in circuit between fuse and transaxle 20-pin harness connector. After repair is complete, go to step 8.
3. Select "A/T Outputs, 1-2 Sol". Cycle 1-2 shift solenoid on and off 3 times. If 1-2 shift solenoid valve clicks when cycled on, go to DIAGNOSTIC AIDS. If 1-2 shift solenoid valve does not click when cycled on, turn ignition off. Disconnect transaxle 20-pin harness connector. Connect a test light between terminal "A" and terminal "E" of transaxle 20-pin harness connector (PCM side). Turn ignition switch to ON position. DO NOT start engine. If test light is off, go to next step. If test light is on, check for short to ground in 1-2 shift solenoid valve control circuit between transaxle 20-pin harness connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
4. Cycle solenoid on and off 3 times. If test light cycles on and off 3 times, go to next step. If test light does not cycle on and off 3 times, check for an open in 1-2 shift solenoid valve control circuit between transaxle 20-pin harness connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, and test light is always off, check for short to voltage in 1-2 shift solenoid valve control circuit between transaxle 20-pin harness connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
5. Turn ignition off. Connect jumper harness (J 39775) to transaxle side of 20-pin harness connector. Connect DVOM between terminal "A" and terminal "E" at jumper. If resistance is 20-40 ohms, replace PCM, then go to step 8.
6. If resistance is less than 50 ohms, go to next step. If resistance is more than 50 ohms, check for open in 1-2 shift solenoid valve power and control circuits between transaxle 20-pin harness connector and solenoid. Repair circuit(s) as necessary, then go to step 8. If circuits are okay, replace 1-2 shift solenoid, then go to step 8.
7. Connect ohmmeter between ground and terminal "A" at jumper. If resistance is less than 100 ohms, check for short to ground in circuit between transaxle 20-pin harness connector and 1-2 shift solenoid. Repair circuit as necessary, then go to next step. If circuit is okay, replace 1-2 shift solenoid, then go to next step.
8. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Start engine and allow to run for 30 seconds. Select "Specific DTC" and enter DTC "P0753". If DTC P0753 is not present, repair is complete. If DTC P0753 is still present, repeat test.

Inspect PCM, transaxle and 1-2 shift solenoid connectors for bent, broken or backed out terminals.

P0756, 2-3 SHIFT SOLENOID ("B") (PERFORMANCE PROBLEM)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS.

PCM identifies a 2-3 shift solenoid problem by monitoring commanded gear and speed ratio. DTC P0756 will set if PCM detects a gear ratio outside limits when 1st gear is commanded.

Conditions For Setting DTC P0756

DTC will set under the following conditions

1. DTC P0101, P0102 or P0103 (MAF sensor) is not present.
2. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTC P0716 or P0717 (input speed sensor) is not present.
5. DTCs P0753 (shift solenoid "A" electrical problem) or DTC P0758 (shift solenoid "B" electrical problem) are not present.
6. DTC P1810 (transmission fluid pressure switch) is not present.
7. Engine has been running for 5 seconds.
8. Vehicle speed is more than 4 MPH.
9. Vehicle is not in fuel shut off mode.
10. Transaxle temperature is more than 86°F (30°C).
11. Transaxle shift is not in progress.
12. Throttle angle is more than 11 degrees.
13. Transmission fluid pressure manual valve position switch indicates D1, D2, D3 or D4.

DTC P0756 will be stored in PCM history and MIL will light. SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM will command 2nd gear and default line pressure. PCM disables state and shift adapts. PCM inhibits TCC and torque management. DTC has 4 different failure criteria. These criteria are as follows

1st gear is commanded. Gear ratio is .65-.71 for one second. Delivered torque is more than 60 lbs. (82 N.m).

2nd gear is commanded. Gear ratio is .95-1.05 for .5 seconds. Delivered torque is more than 60 lbs. (82 N.m).

3rd gear is commanded. Gear ratio is 1.51-1.71 for 4 seconds. Delivered torque is more than 60 lbs. (82 N.m).

4th gear is commanded. Gear ratio is 2.87-3.11 for 1 second. Delivered torque is more than 16 lbs. (22 N.m).

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "A/T Output" then select "Shift Trans". Monitor current gear and ratio data pairs. Accelerate vehicle and command 1st gear. If gear ratio is not .65-.71, go to next step. If gear ratio is .65-.71, inspect and repair the following, see HYDRA-MATIC 4T80-E overhaul article then go to step 6: Lo/Reverse servo apply pin. 2-3 shift valve stuck. Forward and/or coast clutch support seals or studs are damaged. Lo roller clutch worn or damaged. Forward clutch piston or seals damaged. Support housing seal rings. Forward sprag. Check ball No. 8 missing.
3. Accelerate vehicle and command 1-2 shift. If gear ratio is not .95-1.05, go to next step. If gear ratio is .95-1.05, inspect and repair the following, see HYDRA-MATIC 4T80-E overhaul article then go to step 6: 2nd clutch plates burnt. 2nd clutch piston or seals damaged. 2-3 shift solenoid valve stuck. 2nd clutch return spring and retainer assembly broken or out of position.
4. Accelerate vehicle and command 2-3 shift. If gear ratio is not 1.54-1.71 go to next step. If gear ratio is 1.54-1.71, inspect and repair the following, see HYDRA-MATIC 4T80-E overhaul article then go to step 6: 3-4 shift valve bore plug is misassembled. Exhaust valve cup plug for driven support or valve installed incorrectly. 3rd clutch plates burnt or damaged. 3rd clutch piston or seals damaged. Check ball missing or stuck. Debris in 2-3 shift solenoid valve.
5. Accelerate vehicle and command 3-4 shift. If gear ratio is not 2.87-3.11, see DIAGNOSTIC AIDS. If gear ratio is .65-.71, inspect and repair the following, see «AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-overhaul-testing-4t80-e) article then go to next step: Debris in 2-3 shift solenoid valve. 4th band or 4th servo. 3-4 shift valve bore plug is misassembled.
6. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Test drive vehicle. Ensure transaxle upshifts and downshifts correctly. Select "Specific DTC" and enter DTC "P0756". If DTC P0756 is not present, repair is complete. If DTC P0756 is still present, see «COMPONENT TESTS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) .

Inspect transaxle fluid for sediment or debris.

P0758, 2-3 SHIFT SOLENOID ("B") (ELECTRICAL PROBLEM)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

2-3 shift solenoid is used to control transaxle fluid to 2-3 shift valve. Ignition voltage is provided to solenoid through fused circuit. See WIRING DIAGRAMS . Ground is provided by Output Driver Module (ODM) within PCM. PCM monitors voltage levels at ODM. When 2-3 shift solenoid is commanded on, PCM will detect low voltage. When 2-3 shift solenoid is commanded off, PCM will detect high voltage. DTC P0758 will set if voltage limits do not meet calibration at anytime.

Conditions For Setting DTC P0758

DTC will set under the following conditions

1. DTC P1650 (ODM) is not present.
2. Engine has been running for more than 5 seconds.
3. PCM detects a circuit problem on 2-3 shift solenoid valve circuits in 5 seconds.

DTC P0758 will be stored in PCM history and MIL will light. SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM will command 2nd gear and default line pressure. PCM disables state and shift adapts. PCM inhibits TCC and torque management.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. If DTCs P0753 or P1860 are present, go to next step. If DTCs P0753 or P1860 are not present, go to step 3.
2. Remove and inspect appropriate fuse. See «WIRING DIAGRAMS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . Replace fuse if necessary. If fuse is blown, check for short to ground in circuit between fuse and transaxle 20-pin harness connector. If fuse is okay, check for open in circuit between fuse and transaxle 20-pin harness connector. After repair is complete, go to step 8.
3. Select "A/T Outputs, 2-3 Sol". Cycle 2-3 shift solenoid on and off 3 times. If 2-3 shift solenoid valve clicks when cycled on, go to DIAGNOSTIC AIDS. If 2-3 shift solenoid valve does not click when cycled on, turn ignition off. Disconnect transaxle 20-pin harness connector. Connect a test light between terminal "A" and terminal "E" of transaxle 20-pin harness connector (PCM side). Turn ignition switch to ON position. DO NOT start engine. If test light is off, go to next step. If test light is on, check for short to ground in 2-3 shift solenoid valve control circuit between transaxle 20-pin harness connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
4. Cycle solenoid on and off 3 times. If test light cycles on and off 3 times, go to next step. If test light does not cycle on and off 3 times, check for an open in 2-3 shift solenoid valve control circuit between transaxle 20-pin harness connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, and test light is always off, check for short to voltage in 2-3 shift solenoid valve control circuit between transaxle 20-pin harness connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
5. Turn ignition off. Connect jumper harness (J 39775) to transaxle side of 20-pin harness connector. Connect DVOM between terminal "A" and terminal "E" at jumper. If resistance is 20-40 ohms, replace PCM, then go to step 8.
6. If resistance is less than 50 ohms, go to next step. If resistance is more than 50 ohms, check for open in 2-3 shift solenoid valve power and control circuits between transaxle 20-pin harness connector and solenoid. Repair circuit(s) as necessary, then go to step 8. If circuits are okay, replace 2-3 shift solenoid, then go to step 8.
7. Connect ohmmeter between ground and terminal "A" at jumper. If resistance is less than 100 ohms, check for short to ground in circuit between transaxle 20-pin harness connector and 2-3 shift solenoid. Repair circuit as necessary, then go to next step. If circuit is okay, replace 2-3 shift solenoid, then go to next step.
8. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Start engine and allow to run for 30 seconds. Select "Specific DTC" and enter DTC "P0758". If DTC P0758 is not present, repair is complete. If DTC P0758 is still present, repeat test.

Inspect PCM, transaxle and 2-3 shift solenoid connectors for bent, broken or backed out terminals.

P1810, TRANSAXLE FLUID PRESSURE (TFP) (VALVE POSITION SWITCH CIRCUIT PROBLEM)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS.

PCM calculates gear ratio from input and output speed sensors. PCM compares known gear ratio to calculated ratio for each gear selected. DTC P1810 detects steady state adapts at maximum and incorrect gear ratio due to excessive transaxle slip.

Conditions For Setting DTC P1810

DTC will set under the following conditions

1. DTC P0101, P0102 or P0103 (MAF sensor) is not present.
2. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTC P0716 or P0717 (input speed sensor) is not present.
5. Ignition voltage is 10-17 volts.
6. Not in fuel shut off mode.

DTC P1810 will be stored in PCM history and MIL will light. SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM substitutes value of previous TFP valve switch, if consistent with Park/Neutral status. PCM commands default line pressure. PCM disables state and shift adapts. PCM inhibits TCC and torque management. DTC has 5 different failure criteria. These criteria are as follows

Engine is running for more than 4 seconds. An illegal TFP valve position switch value of 000 or 010 for 4 seconds.

Engine is running for more than 5 seconds. Vehicle speed is more than 11 MPH. Throttle angle is more than 11 degrees. Delivered torque is 80-200 ft. lbs. (109-270 N.m). TFP valve position switch shows Park/Neutral and gear ratio indicates Reverse or Drive for 4 seconds.

Engine is running for more than 5 seconds. Vehicle speed is more than 11 MPH. Throttle angle is more than 11 degrees. Delivered torque is 80-200 ft. lbs. (109-270 N.m). TFP valve position switch shows Reverse and gear ratio indicates Drive for 4 seconds.

Engine is running for more than 5 seconds. Vehicle speed is more than 11 MPH. Throttle angle is more than 12 degrees. Delivered torque is 80-200 ft. lbs. (109-270 N.m). TFP valve position switch shows D4, D3, D2 or D1 and gear ratio indicates Reverse for 4 seconds.

Criteria No. 5

Engine is off. TFP valve position switch shows D2 and does not indicate Park/Neutral in 4.95 seconds after engine running.

1. Ensure fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. NOTE: All TFP position switch parameters will be given in A/B/C order (Example: ON/OFF/ON). Scan tool will display "ON" and "OFF". "ON" switch is closed and "OFF" switch is open.
2. Select snap shot mode on scan tool and capture "TFP Val Position Sw" data parameter. If TFP position switch parameters are Off/Off/Off, go to step 9. If TFP position switch parameters are On/Off/Off, inspect and repair short to ground in transmission range "A" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, go to step 18. If TFP position switch parameters are not On/Off/Off or Off/Off/Off, go to next step.
3. If TFP position switch parameters are Off/On/Off, inspect and repair short to ground in transmission range "B" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, go to step 18. If TFP position switch parameters are not Off/On/Off, go to next step.
4. If TFP position switch parameters are Off/Off/On, inspect and repair short to ground in transmission range "C" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, go to step 18. If TFP position switch parameters are not Off/Off/On, go to next step.
5. If TFP position switch parameters are On/On/Off, inspect and repair wires shorted together in transmission range "A" and "B" input circuits between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are not On/On/Off, go to next step.
6. If TFP position switch parameters are On/Off/On, inspect and repair wires shorted together in transmission range "A" and "C" input circuits between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are not On/Off/On, go to next step.
7. If TFP position switch parameters are Off/On/On, inspect and repair wires shorted together in transmission range "B" and "C" input circuits between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are not Off/On/On, go to next step.
8. If TFP position switch parameters are On/On/On, inspect and repair wires shorted together in transmission range "A", "B" and "C" input circuits between transaxle 20-pin harness connector and PCM then go to step 24. If circuits are okay, replace PCM then go to step 24.
9. Connect Jumper Harness (J 39775) to PCM side of 20-pin harness connector. Using test Adapter Kit (J 35616), connect fused jumper wire between terminal "N" of jumper and ground. If TFP position switch parameters are not On/Off/Off and are Off/Off/Off, inspect and repair open in transmission range "A" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are not Off/Off/Off, go to next step. If TFP position switch parameters are On/Off/Off, go to step 12.
10. If TFP position switch parameters are not On/On/Off, inspect and repair wires shorted together in transmission range "A" and "B" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are On/On/Off, go to next step.
11. If TFP position switch parameters are not On/Off/On, inspect and repair wires shorted together in transmission range "A" and "C" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are On/Off/On, go to next step.
12. Connect fused jumper wire between terminal "R" of jumper and ground. If TFP position switch parameters are not Off/On/Off and are Off/Off/Off, inspect and repair open in transmission range "B" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are not Off/Off/Off, go to next step. If TFP position switch parameters are Off/On/Off, go to step 15).
13. If TFP position switch parameters are On/On/Off, inspect and repair wires shorted together in transmission range "A" and "B" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are not On/On/Off, go to next step.
14. If TFP position switch parameters are Off/On/On, inspect and repair wires shorted together in transmission range "B" and "C" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are Off/On/On, go to next step.
15. Connect fused jumper wire between terminal "P" of jumper and ground. If TFP position switch parameters are not Off/Off/On and are Off/Off/Off, inspect and repair open in transmission range "C" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are not Off/Off/Off, go to next step. If TFP position switch parameters are Off/Off/On, go to step 18.
16. If TFP position switch parameters are Off/On/On, inspect and repair wires shorted together in transmission range "A" and "B" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. If TFP position switch parameters are not Off/On/On, go to next step.
17. If TFP position switch parameters are On/Off/On, inspect and repair wires shorted together in transmission range "A" and "C" input circuit between transaxle 20-pin harness connector and PCM then go to step 24. If circuit is okay, replace PCM then go to step 24. NOTE: If any circuit in transaxle wire harness needs repair between transaxle 20-pin harness connector and TFP valve position switch, transaxle wire harness MUST be replaced as an assembly.
18. Disconnect Jumper Harness (J 39775) from PCM side and connect to transaxle side of 20-pin harness connector. Connect DVOM between terminal "N" of jumper and ground. If resistance is less than 1000 ohms, inspect and repair short to ground in transmission range "A" input circuit between transaxle 20-pin harness connector and TFP valve position switch then go to step 24. If resistance is more than 1000 ohms, go to next step. If circuit is okay, replace TFP valve position switch then go to step 24.
19. Connect DVOM between terminal "R" of jumper and ground. If resistance is less than 1000 ohms, inspect and repair short to ground in transmission range "B" input circuit between transaxle 20-pin harness connector and TFP valve position switch then go to step 24. If resistance is more than 1000 ohms, go to next step. If circuit is okay, replace TFP valve position switch then go to step 24.
20. Connect DVOM between terminal "P" of jumper and ground. If resistance is less than 1000 ohms, inspect and repair short to ground in transmission range "C" input circuit between transaxle 20-pin harness connector and TFP valve position switch then go to step 24. If resistance is more than 1000 ohms, go to next step. If circuit is okay, replace TFP valve position switch then go to step 24.
21. Start engine and allow to idle. Place gear selector in reverse. Connect DVOM between terminal "N" of jumper and ground. If resistance is more than 5 ohms, inspect and repair open in transmission range "A" input circuit between transaxle 20-pin harness connector and TFP valve position switch then go to step 24. If resistance is less than 5 ohms, go to next step. If circuit is okay, replace TFP valve position switch then go to step 24.
22. Connect DVOM between terminal "R" of jumper and ground. If resistance is more than 5 ohms, inspect and repair open in transmission range "B" input circuit between transaxle 20-pin harness connector and TFP valve position switch then go to step 24. If resistance is less than 5 ohms, go to next step. If circuit is okay, replace TFP valve position switch then go to step 24.
23. Move gear selector to D4 position. Connect DVOM between terminal "P" of jumper and ground. If resistance is more than 5 ohms, inspect and repair open in transmission range "C" input circuit between transaxle 20-pin harness connector and TFP valve position switch then go to step 24. If resistance is less than 5 ohms, replace TFP valve position switch then go to next step. If circuit is okay, replace TFP valve position switch then go to step 24.
24. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Road vehicle in all gears. With vehicle in OD accelerate with throttle angle more than 12 degrees. Vehicle speed must be more than 7 MPH. Engine torque must be 80-200 ft. lbs. (109-270 N.m). Select "Specific DTC" and enter DTC "P1810". If DTC P1810 is not present, repair is complete. If DTC P1810 is still present, repeat test.

P1811, MAXIMUM ADAPT & LONG SHIFT

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

When an upshift is commanded, PCM measures interval during which gear ratio leaves current range and changes to reflect commanded upshift. This interval is displayed on scan tool as "Shift Time". When this interval has exceeded a predetermined limit, PCM utilizes shift adapts in order to attempt to shorten shift time. DTC P1811 detects when maximum allowable shift time has been exceeded and upshift adapts have reached their upper limit.

Conditions For Setting DTC P1811

DTC will set under the following conditions

1. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
2. DTC P0502 or P0503 (vehicle speed sensor) is not present.
3. DTCs P0712, P0713 or P0218 (transaxle fluid temperature) are not present.
4. TFT is more than 194°F (90°C).
5. Vehicle speed is more than 10 MPH.
6. Throttle angle is more than 15.7 degrees.

DTC P1811 will be stored in PCM history. MIL will NOT light. SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM commands maximum line pressure. PCM disables all adapts. PCM inhibits torque management.

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. If other DTCs are present, repair those DTCs first then go to step 6.
2. Select "Specific DTC" and enter "Adapts". Review Transaxle Adapt Pressure (TAP) data and compare parameters. See 1-2 ADAPTS table.

1-2 ADAPTS

If data parameters are equal to or more than specified, inspect and repair following then go to step 6

1. Low line pressure.
2. Pressure control solenoid clamp.
3. Pressure control solenoid stuck on.
4. 2nd clutch assembly.
5. 2nd sprag clutch.
6. 1-2 shift solenoid valve.
7. 1-2 shift valves.

See AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E article. If data parameters are less than specified, go to next step.

3) Review data and compare parameters. See 2-3 ADAPTS table.

2-3 ADAPTS

If data parameters are equal to or more than specified, inspect and repair following then go to step 6

1. Low line pressure.
2. Pressure control solenoid clamp.
3. Pressure control solenoid stuck on.
4. 3-4 shift valve bore plug is misassembled.
5. Exhaust valve cup plug for driven support or valve installed incorrectly.
6. 3rd clutch plates burnt or damaged.
7. 3rd clutch piston or seals damaged.
8. Check ball missing or stuck.

See AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E article. If data parameters are less than specified, go to next step.

4) Review data and compare parameters. See 3-4 ADAPTS table.

3-4 ADAPTS

If data parameters are equal to or more than specified, inspect and repair following then go to step 6

1. Low line pressure.
2. Pressure control solenoid clamp.
3. Pressure control solenoid stuck on.
4. 4th band or 4th servo.
5. 3-4 shift valve bore plug is misassembled.

See AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E article. If data parameters are less than specified, go to next step.

5) Connect oil pressure gauge to line pressure test port, see HYDRAULIC PRESSURE TESTS in AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E article. Select "A/T outputs" then "PC Sol" on scan tool. Start engine and allow to idle in park position. Increase and decrease PC solenoid valve amperage and record values. See PCS SPECIFICATIONS table.

PCS SPECIFICATIONS

If scan tool shows specified pressure at amperage, see DIAGNOSTIC AIDS. If pressures are high or low, see HYDRAULIC PRESSURE TESTS in HYDRA-MATIC 4T80-E overhaul article for repair then go to next step.

6) After repair is complete, select DTC on scan tool. Select "Clear Info" function then "A/T Reset Adapts". Road test vehicle in D4. Ensure ATF is more than 196°F (90°C), TP angle is more than 15.7 degrees and vehicle speed is more than 10 MPH. Vehicle must shift 1-2, 2-3 and 3-4 in .55 seconds 3 times. Select "Specific DTC" and enter DTC "P1811". If DTC P1811 is not present, repair is complete. If DTC P1811 is still present, repeat test.

Inspect wiring for poor connections at PCM and at transmission 20-pin connector. Check for possible bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for possible intermittent short or open condition, move wiring harness while observing scan tool for value change. Ensure PCM is latest update. If transaxle overhaul was performed, using scan tool clear all adapts.

P1814, TCC OVERSTRESS

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS.

DTC P1814 detects high throttle angle and low vehicle speed in Drive or Reverse. DTC P1814 is used to record failure data because this condition can damage powertrain.

Conditions For Setting DTC P1814

DTC will set under the following conditions and DTC P1814 will be stored in PCM history

1. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
2. DTC P0502 or P0503 (vehicle speed sensor) is not present.
3. DTC P0716 or P0717 (input speed sensor) is not present.
4. TCC slip speed is more than 1600 RPM.
5. Vehicle speed is less than 5 MPH.
6. Transaxle is in Drive or Reverse.
7. Throttle angle is more than 75 degrees for 12 seconds.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTC 1814 failure counter is "1", inspect and repair transaxle fluid condition and level then go to next step. If DTC 1814 failure counter indicates more than "1", replace transaxle fluid and scavenge screens. Reset transaxle oil life then go to next step. See «TRANSMISSION SERVICING - A/T»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transmission-servicing) article.
3. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Drive vehicle in D4 with TCC slip less than 1504 RPM and throttle angle less than 65 percent. Vehicle speed more than 5 MPH. Conditions must occur for more than 5 seconds. Select "Specific DTC" and enter DTC "P1814". If DTC P1814 is not present, repair is complete. If DTC P1814 is still present, repeat test.

Accelerating and applying brakes at same time may set DTC P1814.

P1860, PULSE WIDTH MODULATED (PWM) (SOLENOID ELECTRICAL PROBLEM)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) fluid is regulated for apply and release by TCC Pulse Width Modulated (PWM) solenoid. When solenoid is commanded off, PCM will detect high voltage. When solenoid is commanded on, PCM will detect low voltage. DTC P1860 will set if voltage limits do not meet calibration at anytime.

Conditions For Setting DTC P1860

DTC will set under the following conditions

1. DTC P0560 (system voltage malfunction) is not present.
2. Engine running for more than 5 seconds.
3. TCC duty cycle is less than 10 percent or more than 85 percent.
4. PCM detects an open, short to ground or short to voltage on TCC PWM solenoid valve circuit in 5 seconds.

DTC P1860 will be stored in PCM history. MIL will light at first failure signal. SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on Drivers Information Center (DIC). PCM will inhibit TCC. PCM will inhibit 4th gear if transaxle is in hot mode.

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Turn ignition off. Disconnect transaxle 20-pin harness connector. Connect a test light between terminal "U" and terminal "T" of transaxle 20-pin harness connector (PCM side). Turn ignition switch to ON position. DO NOT start engine. If test light is off, go to next step. If test light is on, check and repair short to ground in TCC PWM solenoid control circuit between transaxle 20-pin harness connector and PCM. Repair circuit as necessary, then go to step 5. If circuit is okay, replace PCM, then go to step 5.
2. Select "A/T Outputs" then "TCC Enable" on scan tool. Cycle TCC solenoid valve ON and OFF 3 times. If test light cycles on and off 3 times, go to next step. If test light stays off, check and repair open in TCC PWM solenoid control circuit between PCM and fuse/relay center, then go to step 5. See «WIRING DIAGRAMS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . If test light stays on, check and repair short to voltage in TCC PWM solenoid control circuit between PCM and TCC PWM solenoid valve. If circuit is okay, replace PCM, then go to step 5.
3. Connect Jumper Harness (J 39775) to transaxle side of 20-pin harness connector. Connect DVOM between terminal "U" and terminal "T" of jumper. If resistance is not 10-15 ohms, inspect and repair open in TCC PWM solenoid control circuit between PCM and 20-pin harness connector, then go to step 5. If circuit is okay, replace TCC PWM solenoid control valve, then go to step 5. If resistance is 10-15 ohms, go to next step.
4. Connect DVOM between terminal "T" of jumper and ground. If resistance is less than 10 ohms, see DIAGNOSTIC AIDS, problem is intermittent. If resistance is more than 10 ohms, inspect and repair open between terminal "T" of jumper and ground, then go to next step. If circuit is okay, replace TCC PWM solenoid control valve, then go to next step.
5. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Road test vehicle and ensure TCC applies. Increase vehicle until TCC enable turns on. Ensure TCC duty cycle is 10-85 percent for 5 seconds. Select "Specific DTC" and enter DTC "P1860". If DTC P1860 is not present, repair is complete. If DTC P1860 is still present, repeat test.

Inspect PCM, transaxle and PWM solenoid connectors for bent, broken or backed out terminals. Ensure transaxle fluid level is correct.

COMPONENT & WIRING HARNESS RESISTANCE CHECK

1. Install Jumper Harness (J-39775) to transmission 20-pin connector. Using an ohmmeter, measure resistance between specified terminals for each component. (Scheme 67) Compare resistance reading to known values. See «TRANSMISSION COMPONENT RESISTANCE SPECIFICATIONS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) table.
2. If resistance reading is okay, go to next step. If resistance reading is not okay, disconnect wiring harness at component and measure component resistance. Replace component if resistance is not as specified. If resistance is as specified, replace transmission harness.
3. Measure resistance between ground and each terminal at transmission 20-pin connector. (Scheme 67) If resistance is within specification, problem is intermittent. If resistance is low, disconnect wiring harness at component.
4. Measure resistance between component terminals and ground. If resistance is low, replace component. If resistance is high, inspect wiring harness for short to ground. Repair as necessary.

TRANSMISSION COMPONENT RESISTANCE SPECIFICATIONS

Scheme 67

PRESSURE SWITCH ASSEMBLY

1. Install Jumper Harness (J39775) to transmission 20-pin connector. Using DVOM, measure resistance between terminal "N" of 20-pin harness connector and ground. (Scheme 67) If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, inspect and repair range "A" circuit between TFP manual valve position switch and 20-pin harness connector, then go to step 7. See «WIRING DIAGRAMS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If circuit is okay, replace TFP manual valve position switch, then go to step 7.
2. Measure resistance between terminal "R" of 20-pin harness connector and ground. If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, inspect and repair range "B" circuit between TFP manual valve position switch and 20-pin harness connector, then go to step 7. See «WIRING DIAGRAMS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If circuit is okay, replace TFP manual valve position switch, then go to step 7.
3. Measure resistance between terminal "P" of 20-pin harness connector and ground. If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, inspect and repair range "C" circuit between TFP manual valve position switch and 20-pin harness connector, then go to step 7. See «WIRING DIAGRAMS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If circuit is okay, replace TFP manual valve position switch, then go to step 7.
4. Start engine and allow to idle. Place gear selector in reverse. Measure resistance between terminal "N" of 20-pin harness connector and ground. If resistance is more than 5 ohms, go to next step. If resistance is less than 5 ohms, inspect and repair range "A" circuit between TFP manual valve position switch and 20-pin harness connector, then go to step 7. If circuit is okay, replace TFP manual valve position switch, then go to step 7.
5. Measure resistance between terminal "R" of 20-pin harness connector and ground. If resistance is more than 5 ohms, go to next step. If resistance is less than 5 ohms, inspect and repair range "B" circuit between TFP manual valve position switch and 20-pin harness connector, then go to step 7. If circuit is okay, replace TFP manual valve position switch, then go to step 7.
6. Shift gear selector to D4. Measure resistance between terminal "P" of 20-pin harness connector and ground. If resistance is more than 5 ohms, replace TFP manual valve position switch, then go to step 7. If resistance is less than 5 ohms, inspect and repair range "C" circuit between TFP manual valve position switch and 20-pin harness connector, then go to step 7. If circuit is okay, replace TFP manual valve position switch, then go to step 7.
7. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Test drive vehicle. Ensure transaxle upshifts and downshifts correctly. Select "Specific DTC" and enter DTC "P1810". If DTC P1810 is not present, repair is complete. If DTC P1810 is still present, go to step 24 of DTC P1810 under «DIAGNOSTIC TESTS»(/cadillac/deville-concours/1994-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e__diagnostic-tests).

1996 "E" & "K" Body - 4.6L Wiring Diagram (DeVille, DeVille Concours, Eldorado & Seville). Scheme 68

1996 "G" Body - 4.0L Wiring Diagram (Aurora). Scheme 69

See also:
• SYSTEM/COMPONENT TESTS
• TESTS W/CODES
• TESTS W/O CODES
• BASIC TESTING
• AUTO TRANS OVERHAUL - HYDRA-MATIC 4T80-E
• TRANSMISSION SERVICING - A/T
• CLUTCH & BAND APPLICATIONS
• CLEARING TROUBLE CODES
• P0218
• P0502
• P0503
• P0711
• P0712
• P0713
• P0716
• P0717
• P0719
• P0724
• P0730
• P0741
• P0742
• P0748
• P0751
• P0753
• P0756
• P0758
• P1810
• P1811
• P1814
• P1860
• RETRIEVING CODES
• DIAGNOSTIC TESTS